3.0 Overheating problem

[2ndGenToyotaFan]

93 4Runner, 4x4, 5 speed.....

I bought this truck while it was not running.... I pulled the engine apart, and found seized idler bearings on the timing belt, and a lot of fluff that was the only sign of a timing belt having been there.... So I assume it was running when it destroyed the belt. The head gaskets were not blown, but some of the valves were pretty tight causing low compression....

So fast forward a while, I tore the heads off, changed the gaskets, moved some of the valve shims around to better adjust the valves, admittedly most of them were a little tighter than they should be, but it runs great.

The problem is it overheats in short order now that it's running... New water pump, new thermostat (tested), new radiator.... Fan seems to be working fine. Hoses are in decent shape.

I took it for a spin and made it about 1.5 miles before the temp gauge was up above normal... By the time I had made it back that 1.5 miles it was in the red, but I got the hose on it, and cooled it down pretty fast....

So I checked some things out, and tried again the next day, and just let it idle. It seemed to warm up a little faster than a 3.0 should, and it stayed at normal for a couple minutes, but then started climbing....

It turns over fine, so I doubt the problem is in the bottom end (as in it's making too much heat around the bearings etc.)

I have not flushed out the block yet, but I have it pulled apart to get the water pump out again..... Anyone have any thoughts? I'm running out of them....

 

[vipergrhd]

Jerod,Would it be possible that you could switch the head gasket?i just did my head gasket not too long ago but can't remember if there is a left and right.it took me almost 3 mos.to finish the job due to other projects getting in the way.did you sent out the heads to be pressure tested at all?

 

[2ndGenToyotaFan]

I am 99.999999% sure the gaskets are on right. I had used a spare pass side gasket on a drivers side head on a different truck, and it caused intermittent overheating, but not instantly like this....

I am starting to doubt myself on that though.... Why couldn't they be symmetrical.....

 

[snobdds]

Did you burp the cooling system? i sometimes put a piece of paper on outside of the radiator and see if the fan clutch is pulling air through...it should stay tight to the radiator at operating tempature.

Hope you get it.

 

[KLF]

Did you burp the cooling system?

X2

On the 3.0, as you know, the thermostat is on the bottom hose, not the top like in most engines. So if you only fill from the radiator, the engine doesn't get filled with coolant. I did a HG on a 3.0 once and it overheated exactly like you describe. I pulled the top hose off and backfilled the engine with coolant, and it was fine after that. I always did that from then on with every engine (even the 22RE) to avoid this possibly.

 

[Sam Stewart]

I agree with the other guys. Sounds like there is a restriction or an air pocket.

 

[2ndGenToyotaFan]

Could be.... I'll give that a check when I get a chance.... out of town for work for a few days... Yeah! Work!!!!!